P15 Impact of soil moisture assimilation and LSM spinup on WRF forecasts

Santanello, Joseph, Sujay Kumar, National Aeronautics and Space Administration - Goddard Space Flight Center (NASA-GSFC), and Patricia Lawston, Earth System Science Interdisciplinary Center/ NASA-GSFC

The choice of land surface model (LSM) physics and spinup approach greatly influences the initial condition of soil moisture and temperature for WRF forecasts. Recent studies have demonstrated the downstream impact of LSM assimilation and calibration using in-situ and satellite-based soil moisture data on boundary layer and ambient weather evolution. In this study, we implement new approaches for soil moisture assimilation into NASA's Land Information System that enable the assimilation to be performed either in the model space (and grid size; 1km) or the observation space (and grid size; 36km). The impacts of performing DA increments at these scales are then examined in the context of 1km NASA Unified WRF (NU-WRF) case studies, and compared to simulations that use default (e.g. NARR), basic LSM spinup, or direct SMAP-based initial conditions for the land surface.